Woodworking bit



E. G. STEIN. WOODWORKING BIT. APPLICATION FILED JAN-18,192]- Patented Mar. 21,1922.

stares EMIL G. STEIN, OF LOS ANGELES, CALIFOIEtIl'IAi woonwoax me Brr.

vide a bit particularly adaptable as a wood working bit for boring holes in thin veneer and the like.

The invention provides a construction wherein the axial screw at the end of the bit is countersunk so that the bit blades will operatively engage thesurface of the work immediately after the point of the screw has first engaged the work. By this arrangement the blades of the bit will have cut into the surface of the work by the time that the screw of the bit has penetrated the work, and the liability of splitting the work is thereby eliminated.

The invention will be readily understood from the following description of the accompanying drawings in which:

Figure 1 is a side elevation of a bit constructed in accordance with the invention.

Figure 2 is a similar view of the lower end of the bit taken in a plane at right angles to that of Fig. 1.

Figure 3 is a bottom plan view of the bit as shown in Fig. 2.

Figure 4 is a plan view of the work engaged by the bit showing the starting of a hole bored therein by the bit.

Figure 5 is a transverse section on the line 5--5 of Fig. 1.

The improved bit consists of a usual shank 1 having the upper end 2 adapted to be engaged in a usual socket. and also provided with a usual spiral rib 3, which at its lower end forms one of the radial cutting blades of the bit. The other radial cutting blade of the bit is formed upon a rib 4 arranged at the lower end of shank 1 in usual manner between the two lowermost convolutions of spiral 3.

The lower end of shank 1 terminates in a usual axial lead screw 5 adapted to first engage the work when the bit is brought into operative position. In bits as heretofore constructed, this lead screw is projected a considerable distance beyond the blades formed on the lower edges of ribs 3 and 41, and, as a consequence, when boring Specification of Letters Patent. Patentgdl Mum, 21 1922.

Application filed January 18, 1921.

Serial No. 438,173.

through thin veneer and the like, the axial aperture formed by this screw through the work before the blades of the bit engage the work, has tended to cause splitting of.

the veneer. In the present construction, the blades of the bit are so arranged as to engage the work immediately after the point of lead screw 5 is brought into operative position.

As an instance of this arrangement, the ends of ribs 3 and 4 are shown spirally prolongated downwardly beyond the upper end of lead screw 5, as shown at 6, and said prolongations preferably taper to points 7 at the outer peripheries of the ribs. These points are in a plane but slightly above the point of lead screw 5, and, as a consequence, when the bit is employed for boring through thin veneer or the like, as shown at V in Fig. 4:, as soon as the screw 5 has started an axial aperture A, the blades of the bit will start an annular recess R and thereby prevent splitting of the veneer.

It will be understood that the usual longitudinally depending blades 8 are formed upon the under sides of the ends of ribs 3 and 1 at the outer peripheries of said ribs, and these blades are preferably spaced back along the ribs from the prolongations 6 of the same, and, as a consequence, the annular recess R started by the blades of the bit immediately after screw 5 engages the work, will be cut by the tapering and pointed prolongations of the respective ribs which extend downwardly into a plane which is spaced but slightly above the point of the lead screw.

By reference to Fig. 5 it will be seen that at the start of a hole bored by the bit, the annular recess R will be out through the work nearly as deep as the axial aperture A formed by lead screw 5, so that by the time the axial aperture has been formed entirely through the work, the annular recess R will also have penetrated nearly the full thickness of the work,thereby reducing the liability of splitting of the relatively thin material in which the aperture is formed.

I claim as my invention:

A wood working bit comprising a shank, an axially disposed lead screw depending from the lower end of said shank, a pair of oppositely disposed radially arranged blades extending downwardly and out wardly from the lower portion of the shank, which vertically disposed blades occupy the lower outer ends of which blades 00- substantially the same horizontal plane with cupy a plane slightly above the plane occuthe lower outer ends of the radially dis- 10 pied by the point of the lead screw, and posed cutting blades.

5 vertically disposed cutting blades depending In testimony whereof I have signed my from the outer portions of the radially disname to this specification. posed cutting blades, the lower edges of EMIL G. STEIN. 

